Offshore companies connected to 44 of Africa’s 54 countries appear in the Panama Papers leak, according to new research.

More than 1,400 companies in the files of the offshore law firm Mossack Fonseca have names that indicate mining or resource extraction interests – raising fresh concerns about how tax havens can be used to exploit the natural wealth of the world’s poorest continent.

The files contain at least 37 offshore companies with operations in Africa that have been named in legal proceedings or criticised by national or international agencies.

The research was published on Monday by African partners of the International Consortium of Investigative Journalists (ICIJ), which coordinated the initial investigation into the offshore law firm’s leaked files.

Twelve of 17 companies named by Italian prosecutors as being connected to a middleman in an alleged bribery scheme surrounding an Algerian oil and gas deal appear in the files, including one company described as a “crossroads of illicit financial flows”.

Mossack Fonseca was at the centre of the Panama Papers leak. Photograph: Arnulfo Franco/AP

It said: “We have not once in nearly 40 years of operation been charged with criminal wrongdoing. We’re proud of the work we do, notwithstanding recent and wilful attempts by some to mischaracterise it.”

The offshore industry has long protested against the charge that it facilitates the theft of Africa’s natural resources.

A report published in 2014 by a lobbying group for Jersey’s financial services sector argued that tax havens facilitated efficient investment in the developing world, a claim that has been echoed by a US group that lobbies in favour of tax havens.

But such claims have been contradicted by other research into illicit financial flows from Africa. According to a 2015 study commissioned by the African Union and the United Nations Economic Commission for Africa, more than $50bn (£38bn) a year is stolen from countries across the continent via fraud and tax avoidance.